What is "Kol Holech al Gachon" referring to?
Rashi: It refers to a snake, 1 which crawls on its belly; 2 "Kol" incorporates worms and the like.
Torah Temimah: As Hashm said to the snake - in Bereishis, 3:14 "Al Gechoncha Teilech",
"Gachon" means 'bent over and low' (Rashi).
Why does the Torah refer to the snake as "Holech al Gachon? Why does it not call a snake 'a snake'?
Based on the Oznayim la'Torah: The answer to this question lies in another question ? posed by the Or ha'Chayim in Pasuk 39 'Why is the snake (the father of all Tum'os, inasmuch as it was it that caused Adam and Chavah to sin), why is it not listed together the Sheratzim? The answer to both questions lies in the fact that initially it stood on two legs ? in the guise of a human-being and was able to speak; whereas now that it crawls on its belly and is no longer capable of speaking,, it is a Sheretz like other Sheratzim, albeit of the species that is not Tamei, and that is how the Torah describes it here. 1
See also Oznayim la'Torah, who elaborates further.
What is "Kol Holech al Arba referring to"?
Rashi: "Holech al Arba" refers to a scorpion whereas "Kol" incorporates beetles and the like.
What is "Kol Marbeh Raglayim referring to?
Rashi: "Marbeh Raglayim" refers to a centipede which possess legs from head to tail, coming out from both sides (whereas "Kol" incorporates anything that resembles a centipede wholly or in part.
Having already written "Lo Ye'achel" (in Pasuk 41), why does the Torah add "Lo Sochlum"?
Yevamos, 114a: To incorporate a Gadol who feeds a Katan in the prohibition. 1
See also Torah Temimah, note 192.
Why is the 'Vav' in "Gachon" large?
Moshav Zekenim #1: It is the middle letter of the Torah (Kidushin 30a). 1 It hints to the Torah, which was given on the sixth of Sivan. [Torah] is called "Aruchah me'Eretz Midah". Therefore 'Vav' is in the middle, for the Torah was proper to be given at the end of two thousand years from creation, had Avraham not said "ba'Meh Eda." 2 It should have been in the middle of the [six thousand] years of world, excluding the [two thousand years of the] days of Mashi'ach. 3
Moshav Zekenim #2: It alludes to six orders of the Mishnah, six directions (including up and down), six days of Creation, six thousand years of the world.,. It is all in the merit of the 'Vavim' at the top of [almost all of] the Amudim (columns of text in the Torah).
Moshav Zekenim #3: It corresponds to six occurrences of Hashem's name in Tehilim 19 - "Toras Hashem, Pekudei Hashem, Eidus Hashem, Mitzvas Hashem, Yir'as Hashem, Mishp'tei Hashem", and the six words in "Sh'ma Yisrael Hashem Elokeinu Hashem Echad", and in Baruch Shem K'vod Malchuso le'Olam va'Ed.
Moshav Zekenim #4: Holech al Gachon alludes to the snake, which was cursed - "Al Gechoncha Seilech" (Bereishis 3:14). Through it fell six good gifts that Hashem gave to Adam ha'Rishon (Bereishis Rabah 12), therefore it was decreed that it be in the form of a long 'Vav' (without arms or legs), and later Hashem will return [the gifts].
Daf Al ha'Daf (Kidushin 30a, citing R. Y. Alter): It is about five thousand letters after the middle letter! Rather, it is the middle of the seventeen special letters (they are big, small or not read). Machzor Vitri (522 be'Sof, citing R. Yosef Tov Elem) lists about twice as many. Alternatively, it is because we are not fully conversant with the letters of the Torah - as were the Amora'im (Torah Temimah).
This was at Bris Bein ha'Besarim. If the Torah is in order, this was after "Lech L'cha" (when Avraham was seventy-five years old), in the year two thousand and seventy-three. Those who disagree say that it was only five years earlier, so Yetzi'as Egypt was 430 years later. (refer to Sh'mos 12:40:3:1)! Did Hashem delay Matan Torah because He knew that Avraham will say so later?! (PF)
Moshav Zekenim citing Avodah Zarah 9a: The world is six thousand years - two thousand of Tohu (void), two thousand of Torah, and two thousand of the days of Mashi'ach. (Presumably, the days of Mashi'ach are excluded from the calculation, for Mashi'ach was proper to come when they began, just sins have delayed him. (PF)